Toxicological impacts of excessive lithium on largemouth bass (Micropterus salmoides): Body weight, hepatic lipid accumulation, antioxidant defense and inflammation response

The unreasonably anthropogenic activities make lithium a widespread pollutant in aquatic environment, and this metallic element can enter the food chain to influence humans. Therefore, the study was designed to explore the influence of dietary lithium supplementation on body weight, lipid deposition, antioxidant capacity and inflammation response of largemouth bass. Multivariate statistical analysis confirmed the toxicological impacts of excessive lithium on largemouth bass. Specifically, excessive dietary lithium (≥87.08 mg/kg) significantly elevated weight gain and feed intake of largemouth bass. Meanwhile, overload lithium inclusion aggravated the accumulation of hepatic lipid and serum lithium. Gene expression results showed that lithium inclusion, especially overload lithium, promoted the transcription of lipogenesis related genes, PPARγ, ACC and FAS, inhibited the expression of fatty acid oxidation related genes, PPARα and ACO, and lipolysis related genes, HSL and MGL. Meanwhile, high lithium inclusion caused the oxidative stress, which was partly through the inhibition of Nrf2/Keap1 pathway. Moreover, dietary lithium inclusion significantly depressed the activity of hepatic lysozyme, and promoted the transcription of proinflammation factors, TNF-α, 5-LOX, IL-1β and IL-8, which was suggested to be regulated by the p38 MAPK pathway. Our findings suggested that overload lithium resulted in increased body weight, hepatic lipid deposition, oxidative stress and inflammation response. The results obtained here provided novel insights on the toxicological impacts of excessive lithium on aquatic animals.